Patent GB-343876-A (GB)
Title: Improvements in or relating to sound recording and reproducing machines
IPC: G11B15/22
Filed: 1929-10-14
Abstract: 343,876. Recording and reproducing sound. WHITE, A. E., 5, Quality Court, Chancery Lane, London.-(Chipman, A. Le R. ; 10, Bridge Street, New York, U.S.A.). Oct. 14, 1929, No. 31193. [Class 40 (ii).] Magnetic apparatus.-A sound recording and reproducing machine comprises a magnetizable wire movable from one reel to another through a " talking head," and includes a device which is adapted to indicate the passage of any predetermined section of the wire through the talking head. Means may be provided for automatically stopping the movement of the wire in either direction at predetermined points. In the machine shown, two reels 15, 16, between which the sound-record wire passes, are mounted on shafts 13, 14, connected by a driving- belt 17. The shaft 14 is driven by a motor M through a belt 20 and pulley 21. To prevent over-running of the reels, there is applied to each shaft 13, 14 a friction drag device consisting of a disc 48 surrounding the shaft, which disc is held against rotation and is adjustably pressed by a spring 49 against a disc 47 secured to the shaft. The wire passes through a recording and reproducing head 32 of ordinary construction, which is mounted on a post 44 adjustably secured in a socket 45. In order to reciprocate the member 32 as the wire passes between the reels, the socket 45 is mounted on a plate 33 which is slidably supported between guides 34. A to-and-fro movement is imparted to the plate 33 by means of a cam 36 and a roller 37 on a slide-block 38, to which block the plate 33 is resiliently connected. The cam 36 is fixed on a shaft 28, driven by a shaft 22 which is itself driven by worm gearing from the shaft 13. The shaft 28 drives through wheels 29, 30 a shaft 31 mounted in bearings on the underside of a frame plate 10, rotation being transmitted from the shaft 31 through a cross-shaft 57 to a shaft 61 which is screw-threaded at 66, The screw carries a nut 67 from which an indicating pointer 70 projects upwardly and travels over a scale 53 fixed to a block 52 near the front of the plate 10. The markings on the scale may correspond with the number of turns of wire on the reel 16, and by noting the readings of the pointer, any selected section of the sound-record may be passed through the reproducing head. A reversing switch of special construction is provided in the circuit of the motor, to allow the wire to be drawn off the reel 16 during recording or reproducing or to be rewound on this reel when desired. The switch may be controlled electromagnetically by means of contacts arranged in conjunction with the indicator nut 67, as subsequently described. By this means automatic stopping of the travel of the record wire in either direction at any predetermined points, corresponding to the beginning and end of a particular selection of the recorded matter, may be effected. The switch, Fig. 2, comprises a fixed block 109 having two rows of contacts a, e, four in each, and a pivoted block 110 carrying four contacts a<1>. The block 110 is pivoted between uprights 111, and is normally held by springs 113 so that the contacts thereon lie between the rows of contacts on the fixed block. By depressing either of two spring- controlled plungers 115 adapted to engage with arms 114 secured to the pivoted block, the latter may be swung so that the contacts a<1> thereon engage with either the row a or the row e on the block 109, so as to complete the motor circuit. Swinging the block from one contact-closing position to the other changes the direction of the current through the field magnet of the motor, and this reverses the rotation. The swinging block is held in either of the circuit-closing positions by a spring latch connected to the armature of an electromagnet (not shown). When this magnet is energized, either by closing a manual switch, or by the automatic closing of the contacts associated with the indicating device, the switch moves so as to break the motor circuit and the machine is stopped. The contact device associated with the indicator comprises a contact pin having its ends 83, 100 projecting from both sides of the nut 67, Fig. 2. Adjustably fixed in line with the contacts 83, 100 are two contacts 91, 99. These can be set to any desired position, so that after a predetermined travel of the nut 67 in either direction has occurred (according to whether the wire is being unwound from or rewound on the reel 16), contacts 83, 91 or 100, 99 engage and complete a circuit through the magnet which enables the main switch to stop the motor. To facilitate setting of the contact 91, it is mounted, under spring control, on a block.72, which can be moved along a suitably graduated slot 93, a set screw 94 being provided to secure the block in the adjusted position. The contact 99 may be slidably mounted in a block 64. In order to stop the machine automatically by mechanical means, should the contact devices described fail to operate, a slidable bar 146 is provided behind the feed screw 66, and is adapted to be shifted in one or other direction when a finger 154 on the nut 67 strikes either of the adjustable adjustments 150 on the bar. When such shifting of the bar occurs, a bellcrank lever 158 is moved by engagement with a notch in the bar, and effects movement of the latch associated with the main switch, so that the latter is allowed to move and open the circuit of the driving motor. A modification of the means of shifting the bar 146 longitudinally is described. Reference has been directed by the Comptroller to Specifications 7292/03 and 425/08, [both in Class 40, Electric telegraphs &c.].